1. Field of the Invention
The present invention relates to an editing machine for inserting a desired signal into a desired portion of a prerecorded signal and for erasing segments of a prerecorded signal and then moving the following signal portion forward so as to prevent a blank portion. This kind of edit is known as nonlinear edit.
2. Description of the Related Art
Nonlinear edit has been heretofore done on media which can be random-accessed on a real-time basis such as magnetic disks, optical disks, and semiconductor memories. However, these media have much smaller storage capacities than the capacity of magnetic tape and so they find only limited use. On the other hand, a recorder using a magnetic tape as its recording medium is unable to gain random access to the medium on a real-time basis and, therefore, very numerous operations are necessary to accomplish a nonlinear edit. Also, a very long time is required to perform the edit.
A method of performing a nonlinear edit is now described while taking a video tape recorder as an example. As shown in FIG. 8, successive segments a.sub.0, a.sub.1, . . . , a.sub.6 of a video signal are recorded on a tape T.sub.A. Successive segments b.sub.3, b.sub.4, and b.sub.5 of another video signal are recorded on another tape T.sub.B. It is assumed that the successive segments b.sub.3, b.sub.4, and b.sub.5 of the second video signal should be inserted between the segments a.sub.2 and a.sub.3.
As shown in FIG. 9, the video signal recorded on the tape T.sub.A is dubbed onto the other tape by the use of two VTR units 1A and 1B, thus creating a copied tape T.sub.A '.
FIG. 10 shows an editing machine. VTR units 2A, 2B, and 2C play back tapes T.sub.A, T.sub.B, and T.sub.A ', respectively. Reproduced video signals V.sub.A, V.sub.B, and V.sub.C produced from the VTR units 2A, 2B, and 2C, respectively, are supplied to a switcher 3. Playback operations of the VTR units 2A-2C and switching operation of the switcher 3 are controlled by an editor 4.
The VTR units 2A-2C are controlled in such a way that the reproduced video signals V.sub.A, V.sub.B, and V.sub.C have a phase relation as shown in FIG. 11. The switcher 3 selects the video signal V.sub.A prior to instant of time t.sub.1. The switcher selects the video signal V.sub.B during the interval between t.sub.1 and t.sub.2. Subsequently, the switcher selects the video signal V.sub.C.
In this way, a video signal consisting of successive segments a.sub.0, a.sub.1, a.sub.2, b.sub.3, b.sub.4, b.sub.5, a.sub.3, . . . can be obtained from the switcher 3. This output video signal is recorded by another VTR unit (not shown). As a result, a nonlinear edit as shown in FIG. 8 can be accomplished.
Then, a situation in which the segments a.sub.2, a.sub.3, a.sub.4, and a.sub.5 are deleted from the successive segments a.sub.0, a.sub.1, . . . a.sub.8, a.sub.9 of a video signal recorded on the tape T.sub.A to obtain successive segments a.sub.0, a.sub.1, a.sub.6, a.sub.7, . . . of the video signal as shown in FIG. 12 is described.
Referring to FIG. 9, a video signal recorded on the tape T.sub.A is dubbed onto another tape by the use of two VTR units 1A and 1B to create a copied tape T.sub.A '.
FIG. 13 shows an editing machine. VTR units 5A and 5B play back tapes T.sub.A and T.sub.A ', respectively. Reproduced video signals V.sub.A and V.sub.B produced from the VTR units 5A and 5B, respectively, are supplied to a switcher 6. Playback operations of the VTR units 5A and 5B and switching operation of the switcher 6 are controlled by an editor 7.
The VTR units 5A and 5B are controlled in such a way that the reproduced video signals V.sub.A and V.sub.B have a phase relation as shown in FIG. 14. The switcher 6 is so controlled that it selects the video signal V.sub.A prior to instant of time t.sub.3 and the video signal V.sub.B after the instant of time t.sub.3. In this way, the output signal from the switcher 6 consists of successive segments a.sub.0, a.sub.1, a.sub.6, a.sub.7, etc. This output video signal is recorded by a separate VTR unit (not shown). As a result, a nonlinear edit as shown in FIG. 12 can be performed.
In order to perform a nonlinear edit by this conventional editing machine, it is necessary to perform a dubbing operation, for previously creating a copied tape. Also, in order to insert other signal, the three VTR units 2A-2C, the switcher 3, and a separate recording VTR unit are necessary. To delete a part of a prerecorded signal, the two VTR units 5A and 5B, the switcher 6, and the separate recording VTR unit are needed. In this way, a nonlinear edit requires a number of VTR units.